Thermal treatment for soybean flour processing with high‐quality color and reduced Kunitz trypsin inhibitor

Abstract

In this work thermal treatment was applied in whole soybean flour and bleached whole soybean flour production aimed at Kunitz trypsin inhibitor (KTI) reduction and color. A 22 Central Composite Rotational Design was developed to evaluate the effects of temperature (91.80–148.20 °C) and time (15.9–44.10 min). In general, the bleached whole soybean flour presented higher KTI reduction and better color than whole soybean flour in the evaluated temperature and time ranges. It was observed that at 148.2 °C for 30 min the whole soybean flour presented a lower KTI value (1.56 mg/g) than bleached whole soybean flour (1.48 mg/g) and good luminosity. As the bleached presents an extra step in the treatment process, new experiments were made with whole soybean flour without bleached to evaluate KTI and color reduction as a time function (10–30 min) at 148.2 °C. The time was evaluated the verify the behavior of KTI and color of whole soybean flour. The treatment at 148.2 °C for 20 and 30 min presented the lowest KTI values, however, the L* color value at 20 min was higher and soybean flour was whiter, hence 20 min was considered the best condition for whole soybean flour production. Practical applications In order to increase the nutritional quality of soybeans and use them as food, the inactivation of protease inhibitors is required. As soybean nutritional value is adversely affected by protease inhibitors presence that are considered anti‐nutritional factors, these need to be eliminated. Thermal treatment has been used as a physical method to inactivate these factors. However, it must be controlled to avoid essential amino acids destruction. Thermal treatment prior to soybean processing for flour production is common. However, recommendation for the best time and temperature for the grains is nonexistent in order to inactivate and/or reduce their phytochemicals with anti‐nutritional action, to the detriment of those with functional effect, preserving their nutrients. Usually, commercial soybean products are thermally treated with less than 20% of in natura soybean trypsin inhibitory activity.

Properties of tofu coagulated with Cardoon flower (Cynara Cardunculus L.)

“…There was a reduction of 93% in KTI value in the tofu compared to soymilk, indicating that the process contributed to obtaining a healthier product. All tofu samples showed minimum residual levels of KTI (Table 1), which is accepted for human consumption, and is within the reduction of up to 80% in inhibitor (Dahmer et al, 2018). Ureatic activity index values are in the range considered for inactivation of the enzyme (0.05 to 0.3 pH unit) (Olguin et al, 2003).…”

“…However, although, these enzymes can be inactivated by heat treatment near 100 °C for 5 to 10 min (Stanojevic, Barać, Pešić, & Vucelic-Radovic, 2020), soybean cultivars, genetic developed for free lipoxygenases and smoother flavor will have characteristics more suitable for human consumption. At Embrapa, soybean genetic improvement for human consumption has developed cultivars that could increase soybean consumption, by stimulating the development of soy-based products with better characteristics (Cantelli et al, 2017;Dahmer, Rigo, Steffens, Steffens, & Carrão-Panizzi, 2018;Schmidt, Cantelli, Steffens, Steffens, & Zeni, 2017). Therefore, quality of tofu may be affected by soybean varieties, chemical components and biologically active compounds (Stanojevic, Barac, Pesic, & Vucelic-Radovic, 2011).…”

Evaluation of packaging systems with O2-absorbers on quality of minimally processed soybean sprouts

“…Among these type of foods, soy sprouts could be a potential alternative, since it is a natural food, good for human health, obtained from germination of grains, developing in a short period of time (5 days), without application of fertilizers or pesticides' (Cantelli et al, 2017). Soy sprouts have been recognized as functional food products and highly nutritious, rich in phytochemicals, vitamins, minerals, enzymes, and amino acids (Dahmer et al, 2018(Dahmer et al, , 2020Losado et al, 2018;Rigo et al, 2015).…”

Design and development of an automated soy chaap making machine

“…To address this problem, people have been relying on plant‐based proteins. Soybean is one of the richest sources of protein produced in many counties like United States, Brazil, Argentina, China, and India, it contains about 40% proteins and is highly digestible to the human after proper heat treatment (Dahmer, Rigo, Steffens, Steffens, & Carrão‐Panizzi, 2018; Giri & Mangaraj, 2012; Mangaraj, Swain, & Deshpande, 2018; Tripathi et al, 2015). Soybean has been used to produce various products, of which soy milk has become commercially popular due to its nutritional profile and suitability for lactose intolerant people (Giri & Mangaraj, 2014; Giri, Mangaraj, Sinha, & Tripathi, 2017).…”

“…treatment (Dahmer, Rigo, Steffens, Steffens, & Carrão-Panizzi, 2018;Giri & Mangaraj, 2012;Mangaraj, Swain, & Deshpande, 2018;Tripathi et al, 2015). Soybean has been used to produce various products, of which soy milk has become commercially popular due to its nutritional profile and suitability for lactose intolerant people (Giri & Mangaraj, 2014;Giri, Mangaraj, Sinha, & Tripathi, 2017).…”